Based on the function, piles can be classified into _______ types.

The dimension of the bulb in an under-reamed pile can be checked by ______

The settlement of a group of friction piles can be computed on the assumption that ____

The elastic compression Δ L of a pile can be calculated by the expression based on _______

In bored pile, concreting is done by using _______

One of the main advantages of using cased piles are _____

Who was the first to develop a method for placing cast-in-situ concrete piles?

The pile spacing of each pile is taken as ______ diameter of the pile.